1. Field of the Invention
The present invention relates to a ceramic substrate having a metallic layer thereon and a process for manufacturing the same, in which an improved bonding between ceramic substrate containing alumina and a metallic layer of molybdenum and the like is facilitated without requiring a high-temperature heat treatment.
2. Discussion of the Background
Conventionally, Telefunken process has been widely used to facilitate relatively close bonding between ceramic materials and metals.
In the Telefunken process, first, the surface of a ceramic material such as alumina and the like is coated with a paste prepared by mixing molybdenum (Mo) and manganese (Mn) powders with an organic binder. Then, the coated ceramic material is subjected to a heat treatment at the temperature of 1300.degree. to 1700.degree. C. in moisturized forming gas or moisturized hydrogen.
However, since the high-temperature heat treatment is essential for the Telefunken process to obtain a sufficient bonding between the ceramic material and the metallic layer, the adverse effect of the high-temperature on materials adjacent to the ceramic material is unavoidable. Further, many other inconveniences such as low density and high porousity of the bonding layer are also associated with the Telefunken process.